AIIMS 2017 Botany Natural Selection MCQ Question
From the statements given below, which one most likely represents an example of disruptive selection. I. Industrial melanism in peppered moth. II. Population of butterflies that are either all yellow or all blue. III. Population of rabbits that evolves more body fat in response to a cold climate. IV. Population of wrens that evolves to be smaller at sexual maturity in response to predation pressure.
I
II
III
IV
Correct Answer
Detailed Explanation
Option B represents disruptive selection because it describes a population of butterflies that are either all yellow or all blue, indicating that extreme phenotypes are favored over intermediate ones. This scenario leads to a bimodal distribution of traits, characteristic of disruptive selection, where individuals at both extremes have a selective advantage.
In contrast, option I (industrial melanism in peppered moths) exemplifies directional selection, as it shows a shift towards darker coloration due to pollution. Option III describes a population adapting to a cold climate by increasing body fat, which is an example of stabilizing selection as it favors a trait that enhances survival in a specific environment. Lastly, option IV illustrates a response to predation pressure, suggesting a shift towards smaller size, which is also indicative of directional selection rather than disruptive selection.
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